Meeting Abstract

P1.139  Wednesday, Jan. 4  The Molecular Evolution of Alpha Keratins in Reptiles and Birds BRICKER, E.A.*; GREENWOLD, M.J.; SAWYER, R.H.; University of South Carolina, Columbia; University of South Carolina, Columbia; University of South Carolina, Columbia

Alpha keratins are filamentous proteins in epithelial cells that are necessary for supplying mechanical stability to those cells against stress. There are two main types of alpha keratins based on acidity, one is acidic (Type I) and the other is basic-neutral (Type II). A large protein-family of alpha keratins is found in mammals which provides the structural proteins for the wide array of mammalian epidermal appendages such as hair and nails. BLAST searches were performed against the preliminary genomes of the saltwater crocodile (Crocodylus porosus) and the American alligator (Alligator mississippiensis). Using phylogenetic analyses we compared the alpha keratin protein and nucleotide sequences of one lizard (Anolis carolinensis), three birds ( Taeniopygia guttata , Gallus gallus, Meleagris gallopavo), and the two crocodilians mentioned above. We found three complete Type II keratin sequences, one in the alligator and two in the crocodile. There appears to be two Type II alpha keratin pseudogenes in the crocodile and one in the alligator. Our phylogenetic analyses revealed that two incomplete alpha keratin sequences on the same scaffold in the alligator are more closely related to each other than to any other gene, possibly indicating lineage specific tandem duplication. An orthologous relationship exists between the complete Type II alligator sequence and the Type IIA chicken. The two complete saltwater crocodile Type II alpha keratins formed a paralogous relationship. The sequences found in these crocodilian species suggest lineage specific duplication, like that seen in mammals, although to a much smaller degree.